Irrigation system helps farmers make better use of water

Many growers have been farming fewer and bigger fields to take advantage of gains in efficiency. But fewer and bigger isn't always better when it comes to certain technologies, some producers are finding.

Consider those growing a variety of row crops in New Mexico, for example. Some operations that once had relatively large fields have reversed the trend to reduced field size as they've adopted the technology of drip irrigation.

“Before we began using drip systems, one farm had seven large fields and typically left about 30 percent of its acres out of production,” says Bill Cox, consulting agronomist and owner of CoxCo Ag Services in Las Cruces, N.M. “The grower simply couldn't get enough water on all of his fields with furrow irrigation.”

The farm that had 12 large fields before the operator began installing drip irrigation in the mid-1990s now has 40 smaller fields, says Cox. And the grower no longer leaves out 30 percent of his acreage each year.

Cox, a speaker at the National Alliance of Independent Crop Consultants annual meeting in Memphis, Tenn., said the move from furrow to drip irrigation has brought a number of changes to the farms he consults on.

“In 1993, when we saw the first drip systems in our area, the average green chile pepper yield was about 16 tons per acre,” he said. “With peppers selling for $295 a ton, revenues averaged about $4,400 per acre.

“In 2005, producers with drip irrigation were harvesting an average of 33 tons per acre. With the price still averaging $295 per ton, that meant revenues had climbed to $9,735 an acre. And most growers are farming every acre if they irrigate with drip.”

Cox, a former president of the NAICC, says farmers started slowly, but have been steadily expanding the number of their acres with drip irrigation.

“In 1993, three growers tried it on 80 acres each,” he said. “The cost of installing a system was about $1,000 per acre. Now it's twice that. By 1996, the technology was proven, and the rush was on.”

Drip irrigation offers farmers in the desert Southwest a number of advantages, he says.

Growers have been able to reduce the amount of nitrogen they apply by putting it out through the drip system. Where they were putting out 90 gallons of N solution in three sidedress applications, they're now applying about 40 gallons through the drip.

“Drip irrigation allows us to keep the moisture levels in the field at optimum all the time,” he said. “Growers weren't always able to get around to all their fields often enough with furrow, which is one of the reasons they left some acres out each year. We've also been able to cut our nitrogen usage in half.”

Producers also find they can get equipment in the field when they need it rather than waiting for the soils to dry. “The ground is almost always dry enough to get a sprayer or other large equipment in the field even though you're providing moisture to the plant roots.”

Cox says drip irrigation does seem to require a steep learning curve. “You can forget what you think you know about plant fertility,” he said. “Drip irrigation requires you to change your thinking.”

The early adopters put their drip tubes 12 inches in the ground, he says, but, more recently, farmers have found a 4-inch depth to be better adapted to a wider number of crops. “Lettuce and some of the vegetable crops require shallow or almost surface irrigation. Putting the tape at 4 inches gives us more versatility.”

Although growers may be tempted to save money on drip tape, Cox advises against it. “Cheap tape is cheap tape,” he says. “Some of the higher quality tape that was installed in the first system is still in the soil. The cheap had to be pulled up and replaced after one or two years.”

Farmers also should be careful where they use drip systems because of problems with pests. “Gophers love it,” he says.

Don't expect to save on water use by installing drip irrigation tubing, he says. “Your crops do not use less water with drip irrigation. That need is still there. The water you have goes farther with drip systems.”